Why DFG Ahri was fine - What's wrong with Current Ahri

As far as I can tell, Riot's logic concerning the removal of Assassin Ahri was their belief that it was not healthy to have a mage assassinating carries from a safe range. Charm + DFG + W + Q was enough to kill pretty much any champion not building a magic resist item early on.

But DFG Ahri was balanced. Her winrate was almost exactly 50%, she wasn't overly picked and she was only occasionally seen in LCS while other assassins such as Fizz, Zed, and Leblanc saw much more popularity both competitively and casually. Why is this? If what Riot states her is true regarding her ability to assassinate from such a long range, why is it that other assassins were frequently picked over her? Why wasn't her winrate through the roof (like it is now)?

I believe the answer lies in the DFG cooldown. With the amp on her charm, Ahri was still incapable of assassinating targets unless she was a few kills ahead or she had her DFG active. On a 90 second cooldown, which cannot be reduced by cooldown reduction, this means that unless Ahri succeeds in assassinating with her first 2-3 assassination attempts, she's going to be relying on DFG for kills for the majority of the game. Gated by a 90 second cooldown.

With the removal of DFG came the removal of this 90 second cooldown gate. In an attempt to keep Ahri 'viable' Riot introduced her huge movespeed advantage (and minor buffs to her damage values). The problem with this is that it completely tipped the scales on her periods of strength, giving her almost 100% uptime on assassination potential in addition to very reliable damage. Add to this the fact that people are now rushing Morellonomicon instead of a DFG for 20% CDR and you see even higher uptime on her damaging abilities. This is where Riot went wrong. They tried to keep her strong, but they removed the most important gate that Ahri had, which was that 90 second DFG cooldown.

So how do you solve this issue? Really, I don't know. The 90 second DFG cooldown isn't exactly replaceable. Anything you put in Ahri's kit can and will be reduced by CDR. Just flat nerfing her numbers might work but then she starts feeling unrewarding to play and her assassin feel gets completely removed. Personally I've always like the feeling of Assassin Ahri, and it's still present in the current kit albeit with far too much uptime on assassin potential. Thoughts?